Golf club with low and rearward center of gravity

ABSTRACT

A driver type golf club head formed of a metal shell and having an overall volume of at least 400 cc having a geometry and weight distribution and a unique multi-level striking face that locates the center of gravity of the club head below a horizontal midline of the striking face and further locates the center of gravity behind said striking face at least 38 percent of the distance between said striking face and said rear surface or 42 mm behind the striking face.

BACKGROUND OF THE INVENTION

The present invention relates to golf clubs and in particular to driver type wood or metal wood heads having an improved configuration and ball striking performance.

Golf club heads were originally hand made from blocks of wood having uniform density and weight. There was little or no consideration about the location of the center of mass or center of gravity and how this parameter affected the overall performance of the golf club during the execution of a golf shot. Occasionally these wooden drivers were weighted, usually with lead, to alter the feel of the club as it was swung. In addition the bottom sole was normally provided with a metal bottom sole screwed into the wooden club head to protect the club from damage caused by rough turf, hard ground rocks and stones that were common on early golf courses. These wooden golf clubs have evolved over several centuries from solid wood construction to metals and carbon fiber. Contributing to the design changes is the use of materials such as steel and titanium used more commonly with today's modern golf clubs. The first generation of metal woods was formed using investment cast stainless steel with a pencil neck hosel. They were slightly smaller than the standard wooden driver club heads of the time. Typically the metal wood driver head had a volume of around 150 cc. Because of the relatively small size, the center of gravity, CG, of these club heads was essentially at or near the center of the club head and they were compact and manageable enough to be able to impart maximum energy transfer to the golf ball.

The new materials and manufacturing techniques allowed for changes in the overall geometry of the club heads including improved strength and weight distribution that, in turn, affected the overall performance and shot making ability of the golf club. These club heads became widely accepted and titanium has now become the material of choice for nearly all manufacturers that were producing premium driver type golf clubs. Thus modern driver type golf club heads are typically made of titanium material and became much larger and have an overall volume of at least 400 cc as compared to many of the earlier metal woods that were approximately half that size and smaller. As head sizes increased so did the moment of inertia of the club head, making the club heads more forgiving on off-center impacts on the clubface. Gradually these larger sized club heads gained acceptance and became the norm for driver type metal woods.

The combination of a deeper center of gravity and a taller striking face allowed golfers to hit tee shots that were launched at a higher angle and with less spin compared to earlier constructed drivers. In turn, most golfers were able to achieve longer driving distances using the new generation of titanium club heads. However, the increased geometry of the modern driver club heads typically locates the center of gravity of the club head close to the face and toward the upper parts of the club head. This requires that for a golf ball to be struck opposite the CG, the strike must occur above a horizontal midline of the club head to obtain maximum energy transfer from the golf club to the golf ball while minimizing excess golf ball spin. Some conventional clubs in the marketplace indicate they have a low CG but testing has found that none of these have a CG below a 50% horizontal midline of the face. Similarly conventional clubs claiming a deep CG, actually have a CG location less than 38 percent of the distance between the striking face and/or less than 44 mm from the face.

Golf professionals and some highly skilled amateurs have the ability to adjust the plane of their golf swing to impact the upper portions of the club head on or above the CG of the club head to achieve maximum energy transfer, however most golfers do not have these skills. In fact, approximately 80 to 95 percent of all golfers have limited skills whereby most of their golf shots are struck in an area on the club face that is below the vertical mid-point on the face. This is particularly true when using the longer, more difficult to control, driver type golf clubs.

It became apparent that adjustment of the location of the CG enables golfers of lesser skill to be able to execute better golf shots.

Examples of prior art include a patent to Rugge 5851160 directed to a driver type metal wood golf club having the CG below a face centerline and forward near the striking face. The patent also teaches that the face has a variable thickness.

U.S. Pat. No. 6,800,038 to Willett and U.S. Pat. No. 6,824,475 to Burnett show a metal wood club head with the rear interior of the striking face formed with raised oval shaped thicknesses; see FIGS. 2, 3 and 4.

Willett U.S. Pat. No. 6,997,820 et al shows another example of a metal wood having a variable face thickness.

Williams U.S. Pat. No. 7,166,038 shows a generally square club head with a MOI greater than 4000 g/cm squared.

The Greaney et al application 2012/0172146 shows a metal wood type golf club with a CG location measured from the Z axis and having different material for the crown and sole, a more expensive manufacturing process, and which has the same thickness of the crown, sole and skirt.

Greaney U.S. Pat. No. 8,012,039 discloses a metal wood golf club and teaches the CG is located midway between the face and the rear without any specific reference to the breadth of the club head.

Kinoshita U.S. Pat. No. 5,094,457 shows a driver type golf club with a CG below a midline between the crown and sole. The CG depth is less than 12.446 mm behind the face plane for easier manipulation of the club face.

Application 2014/0302946 to Rae teaches the CG location can be improved by placing mass low and deep in the club head.

Billing's U.S. Pat. Nos. 7,004,852, 7,189,169, 7,344,450, 7,828,672, 8,177,662 and 8,491,413 are directed to driver type golf club heads having a weighting port that allows customizing the location of the center of gravity lower but in a fixed CG depth location due to the orientation of the adjustable weight cavity.

Ballow U.S. Pat. No. 6,716,110 and Billings U.S. Pat. No. 8,382,604 disclose putter type club heads with a rear CG location.

Another Beach U.S. Pat. No. 8,771,102 to shows a metal wood with a CG location low and toward the rear of the club head.

Ferguson U.S. Pat. No. 8,617,000 et al discloses a metal wood golf club with externally protruding rear weights.

Klin U.S. Pat. No. 1,549,993 shows a driver club head with a weight attached into a recess at the rear of the club head.

U.S. Pat. No. 1,659,273 to Link shows a wood type golf club with a rear weight attached by screws.

U.S. Pat. No. 5,669,827 to Nagamoto discloses a metal wood with a laminated weight construction at the rear of the club head for locating the CG rearward of the face of the club head.

U.S. Pat. No. 6,890,267 to Mahaffey et al shows a metal wood with rear peripheral weight and lower surfaces to increase MOI of the club head.

U.S. Pat. No. 7,377,860 to Breier shows a secondary toe and heel weight that create a rearward and low CG.

U.S. Pat. Nos. 6,659,884, 6,659,885, 7,131,912, 7,273,421 and 7,481,717 to Knuth disclose metal wood type club heads with various face geometries and parabolic club head body configurations.

SUMMARY OF THE INVENTIONS

The present invention relates to a driver type golf club head formed of a metal shell body having an overall volume of at least 400 cc and having a geometry and weight distribution that locates the center of gravity of the club head below a horizontal midline of the ball striking face and further locates the center of gravity behind the striking face at least 38 percent of the distance between the striking face and the rear surface or at least 44 mm from the striking face. This creates a moment of inertia, MOI, greater than 5,000 grams per centimeters squared. The lower and rearward CG location and high MOI reduces the spin of a golf ball struck with the club head and creates vertical roll to engage vertical gear effect resulting in the golf ball traveling higher and longer and with less dispersion.

In a preferred embodiment, the location of the CG is accomplished by a unique weight distribution of the sole, side surfaces forming a skirt that joins the crown and the sole and top crown whereby the sole thickness is greater than the thickness of the crown and the skirt and the thickness of the crown is less than the skirt. In this embodiment, the rear wall of the club head shell is approximately twice the thickness of the maximum thickness of the striking face. This thickened structure creates a mass at the rear of the club head that aids in locating the CG rearward of the striking face. In this particular embodiment the CG is at least 44 mm behind the face. In addition, the ball striking face of the driver is formed of multiple sections that are thinner at the upper areas of the face.

An alternate embodiment of the club head of the present invention is essentially the same as the club head described above, the one major difference being the rear wall is not thick and there is no additional mass at the rear. This embodiment locates the CG slightly closer to the face at 42 mm behind the face.

Another feature is a multi-level ball striking face that is applicable for use with the club heads described herein or with more conventional club heads. The striking face is formed with up to seven sections having different thickness levels with a thickest section at a central location on the striking face and with the upper toe and heel sections that are the thinnest sections. The remaining sections are thicker toward the bottom of the face and thinner toward the top of the face in order to locate weight toward the bottom of the club head for the purpose of lowering the CG on whatever type club head the striking face is used with.

Among the objects of the present invention is the provision of a driver type golf club head having improved CG location and increased MOI.

Another object is the provision of a driver having a unique striking face geometry that increases distance and reduces dispersion of a golf ball struck with the driver.

Yet another object is the provision of a driver that provides improved stability, increased ball speed and distance, limited dispersion on off center strikes against the golf ball.

Still another object is the provision of a driver that reduces the spin of a golf ball at impact allowing the ball to travel straighter and longer.

Still a further object is to provide a driver design having low and rearward CG that is more efficient and less costly to produce compared to using different materials for the body and using weight ports.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a golf club head in accordance with the present invention.

FIG. 2 is a front elevational view of the club head of FIG. 1.

FIG. 3 is a toe side elevational view of the club head.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 1.

FIG. 5 is a bottom view of the club head.

FIG. 6 is a top elevational view of the club head.

FIG. 7 is a frontal view of a ball striking face used with the club head of the present invention.

FIG. 7a is a sectional view taken along the line 7 a-7 a of FIG. 7.

FIG. 7b is a sectional view taken along the line 7 b-7 b of FIG. 7.

FIG. 8 is a sectional view of an alternative embodiment of a club head in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings, a golf club head 100 in accordance with the present invention is formed of a hollow metallic shell 101 that is generally conventional in shape and includes a top crown 102, bottom sole 104, heel 106, toe 108, rear surface 110, toe side surface 112, heel side surface 113, ball striking face 114 and hosel 116 for connection to a golf shaft. The crown 102 includes a parabolic shaped, aerodynamic raised surface 118. The bottom sole 104 also includes a parabolic shaped, aerodynamic raised surface 120 that is complimentary to the aerodynamic surface 118 on the crown 102. The ball striking face 114 is a driver type having a loft angle less than 13 degrees and is formed of multiple levels as described in detail below.

As seen in the sectional view of FIG. 4, the metallic shell 101 has a top crown 102 with a thickness of no greater than 0.75 mm, but preferably 0.45 to 0.5 mm, that is less than the thickness of 0.85 mm of the bottom sole. In addition, the toe side and heel side surfaces 112 and 113 have a thickness no greater than 0.75 mm and preferably 0.65 mm or less than the thickness of the bottom sole. There is a transition area 115 between the striking face 114 and the remaining areas of the metallic shell 101 ranging from 2.6 mm wide at the bottom to 1.2 mm wide near the upper parts of the shell 101. It will be appreciated the thickness of the transition area decreases away from the striking face 114 until it becomes the thickness of the remainder of the shell 101, namely the crown 102, the bottom sole 104, toe side surface 112 and heel side surface 113. The variation in the thickness of the structure of the club head 100 concentrates more weight at the bottom of the club head 100 that, in turn, lowers the center of gravity, CG.

An additional rear mass 122 of the same material as the rest of the club head shell 101 is integrally formed with the rear surface 110 having a thickness of at least 6 mm at the widest location. The thickness of the rear mass 122 is approximately twice the thickness of the thickest portion of the striking face 114. The rear mass 122 is located directly centered behind and in-line with the thickest part of the striking face 114 and extends into the interior 124 of the club head 100. This additional, rear mass 122 insures a lower, more rearward CG location.

As further seen in FIG. 4, the CG is at least 44 mm behind the striking face 114, or at least 38 percent of the distance between the striking face 114 and the rear surface 110, but not greater than 50 percent of the distance between the striking face 114 and the rear surface. The CG is also below a horizontal midline HM between a top edge 134 and bottom edge 136 of the striking face 114 and extending rearward between the striking face 114 and the rear surface 110.

Referring to FIGS. 7, 7 a and 7 b, the striking face 114 is shown in more detail, formed with multiple thickness levels. The multi-level ball striking face 114 is applicable for use with the club heads described herein or with more conventional club heads. The striking face 114 has seven separate sections, integrally formed by conventional machining or molding techniques, each having variable thicknesses as described below. The impact area at the center of the striking face 114 is formed as a centrally located, oval shaped section 114 a having a thickness of 3.1 to 3.4 mm that is similar to the thickness of conventional, single thickness driver striking faces. A second section 114 b is also oval shaped and is adjacent to and surrounds the first section 114 a and has a lesser thickness of 2.5 to 3.1 mm. An uppermost section 114 c, adjacent the top crown 102, has a still lesser thickness of 2.2 to 2.6 mm to minimize mass at the upper portion of the striking face 114. This thickness variation further reduces weight at the upper portions of the club head 100 to insure a lower location of the CG no matter what the geometry or weight configuration of the rest of the club head. This upper section 114 c may be tunable to insure an appropriate coefficient of restitution range.

A central section 114 d is located above and partially around outer oval section 114 b and below upper section 114 c and has a thickness of 2.5 to 3.1 mm. A lower section 114 e fills in the bottom of the striking face 114 and has a thickness of 2.4 to 2.6 mm that is thicker than upper section 114 c locating more mass toward the bottom of the club head 100. Sections 114 d and 114 e depict similar wall thicknesses, however slight variations of the thickness of these sections independently of each other allows adjustment of the desired weight requirements and fine tuning of the coefficient of restitution.

A toe section 114 f and heel section 114 g form the outermost areas of the striking face 114 away from the center and are formed with parabolic edges at an interior location on the face 114 that interface with adjoining upper section 114 c, intermediate section 114 d and an upper edge of lower section 114 e. The toe section 114 f and heel section 114 g are thinner in the upper areas of the club head 100 where corner welding support stiffens this area of the club head 100. Toe section 114 f has a thickness of 1.7 to 1.9 mm and heel section 114 g has a thickness of 2.2 to 2.5 mm. Since the toe section 114 f and heel section 114 g are the thinnest and consequently have less mass, placing these sections in an upper portion of the striking face 114 contributes to the lower location of the CG.

The parabolic edges of the toe section 114 f and heel section 114 g are complimentary to the parabolic shaped, aerodynamic raised surface 120 on the bottom sole 104 and to the parabolic shaped, aerodynamic raised surface 118 on the crown 102. The parabolic shape that interfaces with the other striking face 114 sections add additional strength in the heel and toe area and overcomes potential weakness due to the thinner dimensions of the toe section 114 f and heel section 114 g. This structure provides more efficient energy transfer to the golf ball during the execution of a golf shot, particularly when a golf ball is struck away from the center of the club face 114.

FIG. 8 shows a sectional view of an alternative embodiment of a golf club head 200 of the type illustrated and described in FIGS. 1 to 7. In this embodiment the thickness and weight of the striking face 214, top crown 202 and bottom sole 204 are essentially the same as the above described embodiments. This embodiment does not use a rear weight at the rear surface 210 and directly behind the striking face 214. This, in turn, locates the CG slightly closer to the face 214 at 42 mm behind the striking face 214, approximately 2 mm closer to the face 214 than the first embodiment described hereinabove. In this embodiment the top crown is 0.45 mm to 0.5 mm but may be up to 0.75 mm. The skirt, not shown, is approximately 0.75 or greater and is thicker than the crown. The bottom sole is 0.85 mm or thicker and is thicker than the crown and skirt. 

1) A driver type golf club head formed of a metal shell body having a hollow interior and having an overall volume of at least 400 cc; said metal shell body including a top crown, bottom sole, rear wall, side walls between said top crown and said bottom sole and a ball striking face; said golf club head characterized by a geometry and weight distribution that locates the center of gravity of the club head below a horizontal midline between an upper edge of said striking face adjacent said top crown and a lower edge of said striking face adjacent said bottom sole and further locates the center of gravity behind said striking face at least 38 percent of the distance between said striking face and said rear surface; and, said rear wall having a thickness approximately twice the maximum thickness of said ball striking face. 2) The driver type golf club head of claim 1 further defined by the thickness of said ball striking face being approximately 3 mm at the thickest point of said striking face and said rear wall having a thickness of approximately 6 mm. 3) The driver type golf club head of claim 1 wherein the location of the center of gravity is further defined as being at least 44 mm behind said striking face. 4) The driver type golf club head of claim 1 further including a hosel adjacent said heel for attachment of a shaft. 5) The driver type golf club head of claim 1 further wherein said rear wall thickness forms a mass on an inner surface of said rear wall surface. 6) The driver type golf club head of claim 5 wherein said mass is formed of the same material as said shell body and extends at least 6 mm into the interior of said shell in line with a thickest section of said striking face. 7) The driver type golf club head of claim 1 further defined by said striking face being formed of multiple sections, said sections having a variety of different thicknesses. 8) The driver type golf club head of claim 6 wherein said sections include centrally located sections having the greatest thickness of said multiple sections. 9) The driver type golf club head of claim 7 wherein said centrally located sections are oval in shape and further include a first inner oval section and at least one outer oval section surrounding said first inner oval section; said first inner oval section having a first thickness and said outer oval section having a second thickness less than said first thickness. 10) The driver type golf club head of claim 9 wherein said multiple sections are further defined by sections in addition to said oval sections, including an upper section; an intermediate section; and, a lower section; said upper section having a thickness less than the thickness of said intermediate and lower sections; the thickness of said intermediate and lower sections being less than said oval sections. 11) The driver type golf club head of claim 10 wherein said multiple sections further include an additional upper toe section and an additional upper heel section of said striking face having lesser thicknesses than the remaining sections. 12) The driver type golf club head of claim 11 wherein said upper toe section and said upper heel sections include a parabolic edge that interfaces with adjoining sections of said striking face. 13) A driver type golf club head formed of a metal shell and having an overall volume of at least 400 cc including a top crown, bottom sole, rear wall surface, side wall surfaces and a ball striking face characterized by a geometry and weight distribution that locates the center of gravity of the club head below a horizontal midline between an upper edge of said striking face adjacent said top crown and a lower edge of said striking face adjacent said bottom sole and further locates the center of gravity behind said striking face at least 38 percent of the distance between said striking face and said rear surface and as being at least 42 mm behind said striking face; said striking face being formed of multiple sections, said sections having a variety of different thicknesses; including a maximum thickness at a center of said striking face and sections of lesser thickness at upper locations of said striking face. 14) The driver type golf club head of claim 13 wherein said sections include centrally located sections having the greatest thickness of said multiple sections; said centrally located sections are oval in shape and further include a first inner oval section and at least one outer oval section surrounding said first inner oval section; said first inner oval section having a first thickness and said outer oval section having a second thickness less than said first thickness; said multiple sections are further defined by sections in addition to said oval sections, including an upper section; an intermediate section; and, a lower section; said upper section having a thickness less than the thickness of said intermediate and lower sections; the thickness of said intermediate and lower sections being less than said oval sections; said multiple sections further including an additional upper toe section and an additional upper heel section of said striking face having lesser thicknesses than the remaining multiple sections. 15) The driver type golf club head of claim 14 wherein said upper toe section and said upper heel sections include an inner parabolic edge that interfaces with adjoining sections of said striking face. 16) A golf ball striking face for use with a metal wood type golf club head comprising multiple sections, said sections having a variety of different thicknesses; said sections include centrally located sections having the greatest thickness of said multiple sections; additional multiple sections surrounding said centrally located sections each having a thickness less than the thickness of said centrally located sections; said additional multiple sections further being defined by and including an upper toe section and an upper heel section of said striking face; each of said upper toe section and said upper heel section having a thickness less than the thickness of all other sections of the striking face. 17) The golf ball striking face of claim 16 further defined by said upper toe section and said upper heel section each including a parabolic edge at an interior location of the face that interfaces with adjoining sections of said striking face. 18) The golf ball striking face of claim 16 wherein said centrally located sections are oval in shape and further include a first inner oval section and at least one outer oval section surrounding said first inner oval section; said first inner oval section having a first thickness and said outer oval section having a second thickness less than said first thickness. 19) The golf ball striking face of claim 17 wherein said multiple sections are further defined by sections in addition to said centrally located oval sections and said heel and toe sections including an upper section; an intermediate section; and, a lower section; said upper section having a thickness less than the thickness of said intermediate and lower sections; the thickness of said intermediate and lower sections being less than the thickness of said oval sections. 20) A driver type golf club head formed of a metal shell body having a hollow interior and having an overall volume of at least 400 cc; said metal shell body including a top crown, bottom sole, rear wall surface, side wall surfaces between said top crown and said bottom sole and a ball striking face; said ball striking face having a loft angle less than 13 degrees; said golf club head characterized by a geometry and weight distribution that locates the center of gravity of the club head below a horizontal midline between an upper edge of said striking face adjacent said top crown and a lower edge of said striking face adjacent said bottom sole and further locates the center of gravity behind said striking face at least 38 percent of the distance between said striking face and said rear surface; said geometry and weight distribution characterized by said top crown having a first thickness; said bottom sole having a second thickness greater than said crown first thickness and said striking face having a greater thickness at lower sections thereof and lesser thickness at upper ends thereof. 21) The driver type golf club of claim 20 wherein the thickness of said top crown is in a range of 0.45 mm to 0.75 mm; and said bottom sole is at least 0.85 mm. 22) The driver type golf club of claim 21 wherein said top crown is approximately 0.5 mm and a skirt connecting the top crown to the sole is approximately 0.75 mm. 23) The driver type golf club head of claim 20 wherein said golf ball striking face is further defined as comprising multiple sections, said sections having a variety of different thicknesses; said sections include centrally located sections having the greatest thickness of said multiple sections; additional multiple sections surrounding said centrally located sections each having a thickness less than the thickness of said centrally located sections; said additional multiple sections further being defined by and including an upper toe section and an upper heel section of said striking face; each of said upper toe section and said upper heel section having a thickness less than the thickness of the other sections of the striking face.
 24. The driver type golf club head of claim 21 wherein said golf ball striking face is further defined by said upper toe section and said upper heel section each including an inner parabolic edge that interfaces with adjoining sections of said striking face. 